We propose to develop a set of recombinant DNA probes to detect restriction fragment length polymorphisms in human DNA. Using human pedigrees we will construct a human linkage map. This linkage map can be used to examine and map possible genetic disease loci. Our approach will use human recombinant DNA probes and restriction enzymes to define polymorphism by the method of Southern, which permits this analysis with a small sample of DNA from an individual. Using DNA from related individuals in pedigrees under study at U. of Utah by Dr. Mark Skolnick, we will determine linkage relationships.